The yard is part of your curb appeal as you noted two viewings before signing. 

house is single story 800 sq ft.How much value is there in improving the curb / online viewing appeal?

If you're looking for Pros to town homes, consider the following: the HOA generally covers outside appearance, so that will take care of your curb appeal as well as a lot of your weekly maintenance (lawncare, snow removal, landscaping, etc).

I'm expecting an equity boost.  

It's good business, BUT the curb appeal quickly gets trashed - - "oh, there's another rental".

Having an industry that is unique to the area will drive many tourist and boost to the local economy.

Thanks @Mike D'Arrigo , MAREI is growing - we typically have about 150 people at a meeting although we have seen almost 300 in March - but everyone loved our speaker so we had a huge boost.  

If you can come to the city to visit that helps but often, as a majority of properties are "curb offers only", buyers will come out for inspections after the offer is made and then go home and complete the rest of deal form there.

No lawyer needed, just give them a three day notice to vacate, then file eviction with property courts, go to court a few weeks later, wait a week, file to get constable out, put them on the curb.

A plumbing modification that requires digging up the curb trap (or something similar) should cost a few grand.